JP4733364B2 - Cavity exploration device - Google Patents

Description

  The present invention relates to a cavity exploration device for exploring a cavity existing around a small-diameter buried pipe such as a small-diameter sewer pipe.

  A water path that flows along the buried pipe is created by the action of groundwater, etc., and the surrounding earth and sand are drawn to create a cavity in the upper part of the buried pipe, or the lower part of the buried pipe is scoured with water to create a cavity around the buried pipe. There is. Exploring these cavities and repairing them in advance is extremely important in terms of preventing accidents caused by road collapses or buried pipe damage.

  In such exploration of cavities, known underground radars have been used. This subsurface radar includes a pulse generation circuit that generates an electromagnetic wave pulse, a transmission antenna that emits the electromagnetic wave pulse into the ground, a reception antenna that receives a reflected wave reflected back from the cavity, and an antenna housing having a reception circuit. A body, a control device for controlling a pulse generation circuit and a reception circuit, and an exploration image processing device for displaying a cavity based on a reception signal of the reception circuit are used to explore the cavity from the ground surface.

On the other hand, a cavity exploration device for exploring a cavity or the like from the inside of a pipeline is also used. This cavity exploration device is equipped with, for example, a radar device that emits electromagnetic waves and explores cavities and the like from the reflected waves, and is equipped with a radar-equipped vehicle that is movable within a large-diameter buried pipe, and a drive that drives the radar-equipped vehicle There is known one that includes a control device that performs control and a display that displays and outputs the position and distance of a cavity, a search image, and the like (for example, see Patent Document 1).
JP-A-10-90433

  In the above-mentioned ground penetrating radar that explores the cavities around the buried pipe from the ground surface, exploration up to about 3 m underground is the limit, and the small cavity around the buried pipe is buried in the reflected wave from the buried pipe. It was so small that it was difficult to identify.

  On the other hand, what is described in Patent Document 1 can be used only when the inside of a large-diameter pipe is searched in one direction because the radar-equipped vehicle moves through the buried pipe. Therefore, in order to search for a cavity in the upper part of the buried pipe that is particularly susceptible to road depression, the antenna surface is arranged so as to face the upper part of the buried pipe. For this reason, in order to grasp the situation of the entire periphery of the buried pipe, it is necessary to direct the antenna surface to at least both side faces and the lower part in the large-diameter pipe. As a solution to this problem, it is conceivable to provide a rotating mechanism for rotating the antenna surface, but it is difficult to reduce the size for mounting, and it has not been proposed in a cavity exploration device for exploring the inside of a small-diameter pipe. Also, when exploring the side direction of the buried pipe, rotate the cavity exploration device 90 degrees using a device or the like so that the antenna surface faces the side surface in the buried pipe, and when exploring the lower part of the buried pipe, It is also conceivable to travel by rotating the cavity exploration device 180 degrees using a device or the like so that the surface of the buried tube faces downward. However, there are problems in miniaturization and attitude control of the entire cavity exploration device, and there are disadvantages in work efficiency, such as a four-fold increase in the amount of work when exploring in all directions.

  Furthermore, the laid state of the buried pipe is not uniform, and there is always a curved portion where the pipe is bent in the horizontal direction or the vertical direction. Since the cavity exploration device employs a trackless traveling system such as a wheel or a caterpillar, the cavity exploration device rotates when traveling on a curved part in the pipeline, and this rotation causes the direction of displacement by a rotation amount. Will not be able to conduct accurate exploration. The mechanism for returning this rotation is not proposed for small-diameter pipes, so if you want to prevent rotation, you can only apply it to large-diameter pipes that can run without contact with the cavity exploration device at the curved part. The inside of the small-diameter pipeline cannot be explored. On the other hand, if the diameter of the cavity exploration device is made smaller than the diameter of the buried pipe, the distance between the antenna and the inner surface of the pipe increases, and multiple reflection occurs between the antenna and the inner face of the pipe, causing radio wave interference and transmitting outside the buried pipe. The absolute amount of electromagnetic waves to be reduced is reduced. For this reason, the intensity of the reflected wave from the cavity or the like decreases, and it becomes difficult to identify the cavity or the like from the display of the exploration image processing apparatus. Since this multiple reflection occurs at smaller intervals as the center frequency of the radar increases, it is necessary to provide an antenna lifting mechanism so that the antenna surface is as close as possible to the inner surface of the pipe. Since it is necessary to provide such a mechanism, after all, the diameter of the cavity exploration device cannot be made smaller than the diameter of the buried pipe.

  The present invention has been made in view of the above circumstances, and its purpose is to enable exploration of the entire circumference of the buried pipe from the inside of the buried pipe with high accuracy and a single run in a small diameter buried pipe. An object of the present invention is to provide a cavity exploration device that can clearly indicate the positions and distributions of buried pipes and cavities from the information acquired by this traveling.

The present invention is a cavity exploration device for exploring a cavity existing around a buried pipe having a small diameter, having a cylindrical shape that is substantially the same diameter as the inner diameter of the buried pipe, and a part of the outer peripheral surface of the buried pipe. An antenna housing from which a cable having a power line and a signal line is led out from the rear end in the introduction direction into the buried pipe, which is slidably contacted with an inner wall and moved in the buried pipe, and an inlet through which the antenna casing is introduced into the buried pipe A control device that supplies electric power to the antenna housing via the derived cable and receives an exploration signal from the antenna housing, an exploration image processing device connected to the control device, and measures the amount of extension of the cable comprising a distance measuring unit for, in the interior of the antenna housing, the antenna housing of fixedly arranged over the entire circumference, has a curved surface that matches the inner periphery of the curvature of the antenna housing An antenna and the receiving antenna for the transmission of several pairs, a plurality of pulse generating circuit for supplying an electromagnetic wave pulse to search a cavity connected individually the antenna to the transmitting antenna, with the antenna is individually connected to the receiving antenna comprising a plurality of receiving circuits for outputting a search signal according reflection wave of the received said pulse, and rolling meter for detecting the circumferential direction of the rotation of the antenna housing, and to the exploration image processing apparatus, the plurality of receiving Based on the exploration signal transmitted from the circuit, the rotation amount measurement signal measured by the rolling meter, and the amount of feeding of the cable measured by the distance measurement unit, the cavity around the buried pipe to be investigated is determined. An image output means for visual display as a hollow region is provided .

  According to the present invention, in a buried pipe having a small diameter, it is possible to search the entire circumference of the buried pipe from inside the buried pipe with high accuracy and in one run, and from the information acquired by this run, the buried pipe and the cavity, etc. It is possible to provide a cavity exploration device that can clearly indicate the position and its distribution.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view schematically showing a state in which a cavity or the like around an embedded pipe 2 embedded in the ground is being searched using a cavity searching apparatus 1. In this embodiment, the minimum inner diameter of the buried pipe 2 is about 150 mm (millimeters) to 250 mm, and the case of long-distance exploration of several tens of meters (meters) or more will be described.
The buried pipe 2 communicates with a device insertion manhole 3 and the device insertion manhole 4 which is spaced apart from the device insertion manhole 3 by several tens of meters. The buried pipe 2 is connected to the ground by a manhole 3 for device insertion and a manhole 4 for device carry-out.

  A cylindrical antenna housing 5 that moves through the buried pipe 2 is connected to a power / communication cable 6 that supplies power to the antenna housing 5 and transmits search information from the antenna housing 5 to the rear side opposite to the moving direction. The other end of the power / communication cable 6 is connected to a control device 7 that controls transmission and reception of radio waves from the antenna housing 5 and a search image processing device 8 that processes search information and displays a search image. ing. The power / communication cable 6 is wound around a rotary drum 9, and the power / communication cable 6 is drawn out by rotating the rotary drum 9 as the antenna housing 5 moves. The distance of the power / communication cable 6 drawn from the rotating drum 9 is measured by the distance measuring unit 10 to measure the amount of movement of the antenna housing 5 in the buried pipe 2. Since the rotation amount of the rotary drum 9 is proportional to the movement amount of the antenna housing 5, the rotation amount may be measured and replaced with the movement amount of the antenna housing 5. A pulling hook 11 is attached to the front portion of the antenna housing 5 on the moving direction side, and a rope 12 is locked to the hook 11. The antenna housing 5 inserted from the device insertion manhole 3 is pulled by the rope 12 and moves while exploring the buried pipe 2, and is finally carried out from the device carry-out manhole 4. In addition, when short-distance exploration of the cavity around the buried pipe 2 is performed, the antenna housing 5 may be pushed and moved without being pulled by the rope 12. In this embodiment, the cavity exploration device 1 includes an antenna housing 5, a power / communication cable 6, a control device 7, an exploration image processing device 8, a rotating drum 9, and a distance measurement unit 10.

  Next, the configuration of the antenna housing 5 will be described. 2A is a side view of the antenna housing 5, and FIG. 2B is a cross-sectional view taken along the line AA in FIG. 2A. In FIG. 2, the positional relationship between the inner peripheral surface of the buried pipe 2 and the outer peripheral surface of the antenna housing 5 is also shown.

  As shown in the figure, in the antenna housing 5, the entire circumference of the antenna housing 5 is divided into eight so that the entire circumference of the buried pipe 2 can be searched, and eight transmission antennas 13 a to 13 h are arranged, and the antenna Eight receiving antennas 14 a to 14 h are arranged at positions parallel to the transmitting antenna 13 in the longitudinal direction of the housing 5. Thus, a plurality of pairs of transmission antennas 13a to 13h and reception antennas 14a to 14h are provided over the entire circumference of the antenna housing 5. Further, each of the transmission antennas 13a to 13h and each of the reception antennas 14a to 14h has a curved surface that matches the curvature of the outer periphery of the antenna housing 5 so as to match the inner peripheral surface shape of the buried pipe 2.

  The transmission antennas 13a to 13h are connected to pulse generation circuits 15a to 15h for individually supplying electromagnetic wave pulses. Even without providing the pulse generation circuits 15a to 15h, for example, a switch (not shown) is provided from one pulse generation circuit, and electromagnetic wave pulses are sequentially supplied to the entire circumference of the antenna housing 5 under the control of the control device 7. The transmitting antenna to be switched may be switched. The receiving antennas 14a to 14h are individually connected to the receiving circuits 16a to 16h, respectively. Similarly to the pulse generation circuits 15a to 15b, the reception circuits 16a to 16h can be made one by using a switch (not shown).

  Here, the separation between the inner peripheral surface of the buried pipe 2 and the antenna surface will be described. The separation between the inner peripheral surface of the buried pipe 2 and the antenna surface greatly affects the radar performance of the cavity exploration device 1. When the distance between the inner peripheral surface of the buried tube 2 and the antenna surface is increased, most of the electromagnetic wave pulses transmitted from the transmitting antennas 13a to 13h are reflected by the inner surface of the buried tube 2. Due to this reflection, radio wave interference occurs, and the absolute amount of electromagnetic wave pulses transmitted to the outside of the buried tube 2 is reduced. For this reason, the intensity of the reflected wave from the cavity or the like decreases, and it becomes difficult to identify the cavity or the like from the search image displayed in the search image processing device 8. The reflection on the inner peripheral surface of the buried pipe 2 occurs at a smaller distance as the center frequency of the radar increases. For example, when the inner diameter of the buried pipe 2 is 150 mm to 250 mm, the maximum value of the antenna element length divided into eight is 50 mm to 90 mm, and the center frequency of the radar is 1.7 GHz (gigahertz) to 1 GHz. In this case, the inventor has obtained a result that the limit value at which the reflection on the inner peripheral surface of the buried pipe 2 becomes large is 15 mm to 25 mm from the result of the experiment. In this embodiment, the distance of the upper part where the inner peripheral surface of the buried pipe 2 and the antenna surface are farthest and the center frequency of the radar are within the above-mentioned range. Therefore, the radar performance of the antenna housing 5 hardly deteriorates.

  Further, in this embodiment, in order to keep the distance between the inner peripheral surface of the buried pipe 2 and the antenna surface below the limit value described above, the cross section of the antenna housing 5 is circular, and the transmission antennas 13a to 13h and the reception antenna 14a are 14h is a curved surface shape matching the circular curvature, but it may be a shape as shown in FIG. 3A is a side view of the antenna housing 5, and FIG. 3B is a cross-sectional view taken along the line BB in FIG. 3A. In FIG. 3, the positional relationship between the inner peripheral surface of the buried pipe 2 and the outer peripheral surface of the antenna housing 5 is also shown. As shown in the figure, the cross section of the antenna housing 5 is an octagonal shape, and the transmitting antennas 13a to 13h and the receiving antennas 14a to 14h are planar shapes arranged on each side of the octagon. Even if it comprises in this way, the result similar to the case of the antenna housing | casing 5 can be obtained. The cross section of the antenna housing 5 is not limited to an octagonal shape, and any other polygonal shape may be used as long as it satisfies the above limit value. In addition, when the antenna housing 5 is divided into polygonal shapes, the transmission antennas 13a to 13h and the reception antennas 14a to 14h can be arranged in accordance with the inner peripheral surface of the buried pipe 2 as the number of corners increases. Exploration accuracy can be increased. Therefore, it is desirable to make it more polygonal. The material of the antenna housing 5 is made of plastic or wood that transmits electromagnetic waves, and a metal that causes total reflection and does not transmit electromagnetic waves is inappropriate.

FIG. 4 is a cross-sectional view showing a configuration of a rolling meter 17 that is a rotation amount measuring unit that measures the amount of rotation of the antenna housing 5 disposed in the antenna housing 5. The rolling meter 17 includes a fixed shaft 18 whose one end is fixedly connected to the inner surface of the antenna housing 5, a rotary bearing 19 that is fitted to the fixed shaft and whose outer periphery is rotatable in the circumferential direction, and a rotary bearing A light source 22 connected to the power / communication cable 6 and a housing 21 in which a weight 20 is suspended in a lower portion so as to be fitted in an outer periphery of the main body 19 so as to always face in a vertical direction by gravity; 22 and a slit plate 23 which is provided at a position opposed to 22 and fixedly fitted to the fixed shaft 18.
FIG. 5 is a view showing the slit plate 23 as a component of the rolling meter 17 from the front side. The slit plate 23 is punched with 16 slits 23a. The light source 22 is disposed so that the irradiated beam is positioned on the circumferential line of the slit plate 23 including the slit 23a. For this reason, the beam irradiated from the light source 22 is transmitted and not reflected at the slit 23a portion, but is reflected at the slit plate 23 at portions other than the slit 23a portion. The light source 22 detects whether the beam is not reflected by the slit plate 23 (no signal) or reflected (signal present).
Due to such a structure, when the antenna housing 5 rotates, the fixed shaft 18 and the slit plate 23 fixed to the antenna housing 5 rotate together with the antenna housing 5. On the other hand, the housing 21 having the weight 20 at the bottom always faces vertically downward. Since the light source 22 is fixedly installed on the housing 21, the vertical direction is maintained and no rotation occurs. That is, the slit plate 23 rotates with respect to the light source 22. Therefore, the light source 22 detects the presence / absence of a signal based on the presence / absence of the slit 23a of the slit plate 23, and measures the amount of rotation of the antenna housing 5 by counting the number of signals present or absent with a counter (not shown). The accuracy of the amount of rotation is determined by the number of slits 23a provided in the slit plate 23. For example, the number of slits 23a may be 360 in order to obtain an accuracy of 1 degree. As the light source 22, an LED (light emitting diode) or a laser having a high directivity and a small beam can be obtained because it can obtain high resolution.

  Next, the distance measuring unit 10 as a measuring unit will be described with reference to FIGS. 6 is a front view of the distance measuring unit 10, FIG. 7 is a cross-sectional view of the distance measuring unit 10 as viewed from above, and FIG. 8 is a positional relationship between the light source 31 and the slit plate 29 of the distance measuring unit 10. FIG. 9 is a diagram showing the slit plate 29 of the distance measuring unit 10 from the front.

  As shown in the figure, the power / communication cable 6 wound around the rotating drum 9 is fed out as the antenna housing 5 moves. At this time, the power / communication cable 6 moves between the pair of rollers 24 a and 24 b and the other pair of rollers 25 a and 25 b in the distance measuring unit 10. The power / communication cable 6 is pressed between the rollers 24a, 24b and between the rollers 25a, 25b. When the power / communication cable 6 moves, the rollers 24a, 24b, 25a, 25b rotate by friction, and the rollers Each roller fixing shaft 26a, 26b, 27a, 27b fixedly fitted to 24a, 24b, 25a, 25b also rotates together. Any one of these roller fixing shafts 26a, 26b, 27a, 27b, in this embodiment, since the center of the slit plate 29 is fixed to the roller fixing shaft 26b, the slit plate 29 is a roller fixing shaft. It rotates in synchronization with the rotation of 26b. A part of the slit plate 29 passes through the fixed frame 30. The slit plate 29 is punched with 16 slits 29a. The light source 31 is fixedly installed on the fixed frame 30 so as to face the slit plate 29 so that the irradiated beam is positioned on the circumferential line of the slit plate 29 including the slit 29a. For this reason, the beam irradiated from the light source 31 is transmitted and not reflected at the slit 29a portion, but is reflected at the slit plate 29 at portions other than the slit 29a portion. The light source 31 detects whether the beam is not reflected on the slit plate 29 (no signal) or reflected (signal present). Therefore, the light source 31 can detect the presence or absence of a signal based on the presence or absence of the slit 29a of the slit plate 29, and can count the number of signals present or not by a counter (not shown) to measure the number of rotations of the roller fixed shaft 26b. The number of rotations of the roller fixed shaft 26b is proportional to the amount of movement of the power / communication cable 6, that is, the amount of movement of the antenna housing 5. If the outer diameter of the roller fixed shaft 26b is determined, the proportionality constant is also uniquely determined. Determined. That is, the amount of movement of the antenna housing 5 can be measured from the number of rotations measured by the distance measuring unit 10. Note that signals can be detected even if light receiving elements are provided at opposed positions in the fixed frame 30 with the slit plate 29 interposed therebetween so as to receive the irradiation beam of the light source 31. In this case, it is detected whether the light has passed through the slit 29a (with signal) or not (without signal).

  Next, a display example of the search image of the search image processing device 8 based on the received signal obtained when the antenna housing 5 moves in the buried pipe 2 from the device insertion manhole 3 to the device carry-out manhole 4 will be described. . FIG. 10 is a circular cross-sectional view of the search image, and FIG. 11 is a development view of the search image. The exploration image processing device 8 is, for example, a computer device in which a display device is integrated, and each receiving circuit is acquired from each receiving antenna 14a to 14h by executing a program stored in an internal storage unit. Based on the intensity of the reflected wave A / D (analog / digital) converted by 16a to 16h, the rotation amount information indicating the rotation amount measured by the rolling meter 17, and the movement distance information indicating the movement distance measured by the distance measuring unit 10. Then, processing such as image processing is performed, and a circular sectional view and a developed view are displayed.

  The antenna housing 5 having a cylindrical shape is obtained by performing correction based on the rotation position based on the rotation amount information indicating the rotation amount obtained by measuring the reflection intensity information obtained from the receiving circuits 16a to 16h by the rolling meter 17. A circular sectional view of the exploration image at a certain point in the buried pipe 2 can be obtained. For example, as shown in FIG. 10, it can be visually recognized that a cavity is generated below the buried pipe 2 at a certain point. Therefore, by the display of the circular sectional view of the exploration image processing device 8, it is possible to determine the generation direction of the cavity or the like around the buried pipe 2 in the cross-sectional direction, its region, and the distance from the buried pipe 2.

  The surroundings of the buried pipe 2 can be obtained by rearranging the circular cross-sectional views of the search images at a plurality of points thus obtained based on the movement amount information indicating the movement amount of the antenna housing 5 measured by the distance measuring unit 10. A developed view of the exploration image can be obtained. For example, as shown in FIG. 11, it is possible to grasp from which point to which point the cavity generated below the buried pipe 2 visually recognized in FIG. 10. Therefore, the display of the developed image of the exploration image processing device 8 can determine the relationship between the position of the buried pipe 2 and the cavity, and in particular, the cavity area in the laying direction of the buried pipe 2.

  In the buried pipe 2 having a small diameter buried in this way, a plurality of pairs of transmitting antennas 13a to 13h and receiving antennas 14a to 14h are provided so as to cover the entire circumferential direction of the cylinder in the cylindrical antenna housing 5. By arranging the above, the cavity exploration device 1 can enable the exploration of the entire circumference of the buried pipe 2 from within the buried pipe 2 in one run.

  Further, a plurality of pairs of transmitting antennas 13a to 13h and receiving antennas 14a to 14h are arranged in the antenna housing 5 as a curved surface shape matching the inner peripheral surface of the buried pipe 2 to search the cavities and the like with high accuracy, The exploration image processing device 8 displays a circular cross-sectional view and a development view based on the rotation amount of the antenna housing 5 by the distance measurement unit 17 and the movement amount of the antenna housing 5 measured by the distance measuring unit 10. Therefore, it is possible to grasp the exact position and distribution of the cavities existing around the small-diameter buried pipe 2 without requiring the attitude control function and the antenna lifting mechanism. Based on the display of the exploration image processing device 8, it is possible to perform a work for repairing a cavity or the like, and it is possible to prevent an accident due to a road collapse or damage to the buried pipe 2.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying constituent elements without departing from the scope of the invention in the implementation stage.

Sectional drawing which shows schematically the state which is exploring the cavity etc. of the circumference | surroundings of the buried pipe buried in the ground in embodiment of this invention. The figure which shows the antenna housing | casing in the embodiment. The figure which shows the other antenna housing | casing in the embodiment. Sectional drawing which shows the structure of the rolling meter which measures the rotation amount of the rotation direction in the antenna housing | casing in the embodiment. The figure which shows the slit board which is a component of the rolling meter in the embodiment from the front side. The figure which shows the front of the distance measurement part in the embodiment. Sectional drawing which looked at the distance measurement part in the embodiment from the upper side. The figure which shows the positional relationship of the light source and slit plate of the distance measurement part in the embodiment. The figure which shows the slit board of the distance measurement part in the embodiment from the front. The circular sectional view of the search picture in the embodiment. The expanded view of the exploration image in the same embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Cavity exploration device, 2 ... Embedded pipe, 3 ... Device insertion manhole, 4 ... Device carry-out manhole, 5 ... Antenna housing, 6 ... Power / communication cable, 7 ... Control device, 8 ... Exploration image processing device, DESCRIPTION OF SYMBOLS 9 ... Rotary drum, 10 ... Distance measuring part, 13a to 13h ... Transmitting antenna, 14a to 14h ... Receiving antenna, 15a to 15h ... Pulse generating circuit, 16a to 16h ... Receiving circuit, 17 ... Rolling meter

Claims (2)

A cavity exploration device for exploring a cavity existing around a small-diameter buried pipe ,
A power line and a signal from the rear end in the direction of introduction into the buried pipe, having a cylindrical shape substantially the same diameter as the inner diameter of the buried pipe, and a part of the outer peripheral surface slidingly contacts the inner wall of the buried pipe and moving in the buried pipe An antenna housing from which a cable having wires is derived ;
A control device for supplying electric power to the antenna housing via the cable led out from an introduction port for introducing the antenna housing into the buried pipe, and receiving an exploration signal from the antenna housing ;
An exploration image processing device connected to the control device, and a distance measuring unit for measuring the amount of feeding of the cable ;
Inside the antenna housing ,
A plurality of pairs of transmission antennas and reception antennas having a curved surface in accordance with the curvature of the inner periphery of the antenna casing, which are fixedly arranged over the entire circumference of the antenna casing;
A plurality of pulse generation circuits that are individually connected to the transmitting antenna and supply electromagnetic pulses for searching the antenna for a cavity ;
A plurality of receiving circuits that are individually connected to the receiving antenna and output a search signal according to the reflected wave of the pulse received by the antenna ;
A rolling meter for detecting the amount of rotation in the circumferential direction of the antenna housing ;
Comprising
In the exploration image processing device ,
Based on the exploration signals transmitted from the plurality of receiving circuits, the rotation amount measurement signal measured by the rolling meter, and the amount of feeding of the cable measured by the distance measurement unit, A cavity exploration device comprising an image output means for visually displaying a cavity portion of the cavity as a cavity region . The small-diameter buried tube has an inner diameter of 250 mm or less, the transmitting antenna and the receiving antenna are each composed of eight pairs of antenna elements, and each antenna element is in a state where the antenna housing is introduced into the buried tube. 2. The cavity exploration device according to claim 1, wherein the cavity exploration device is close to the inner peripheral surface of the buried pipe at an interval of 25 mm or less .

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